nticks doesn't seem to affect the workings of the explicit plot type in
draw, however the docs say that it does.
eg:
draw(nticks=10,
gr2d(nticks=10,explicit('(sin(x)),x,0,%pi),
nticks=3,
explicit('(sin(x)-.5),x,0,%pi)));
these curves are both equally smooth, unlike the example given in the
docs for nticks (with ellipse).